In vane-type adjusting devices of the aforesaid type commonly known in the art, the sealing of the pressure chambers in the hollow space of the drive pinion against pressure oil leakage is generally effected on the one hand by two narrow radial gaps arranged between the wings of the winged wheel and the circumferential wall and between the hub of the winged wheel and the circumferential wall of the drive pinion, and on the other hand by two narrow axial gaps between the side walls of the wings of the winged wheel and the side walls of the drive pinion. From the manufacturing point of view, it is, however, not possible, or possible only at very high expense, to make two narrow or sealing gaps in radial direction in such vane-type adjusting devices because this results in an overdetermination between the winged wheel and the drive pinion so that one of the radial gaps inevitably does not seal as intended. In spite of complicated manufacturing and a perfect fit of the individual parts of such adjusting devices, increasing leakage of the pressure oil through the radial and axial gaps in excess of the restricted leakage required, per se, occurs with increasing temperature of the pressure oil during engine operation. This leads to a reduction of the oil supply pressure and thus to retarded adjustment and a too weak hydraulic clamping of the winged wheel and thus of the camshaft. This has a strong detrimental effect at high oil temperatures because the viscosity and the oil supply pressure are then particularly low so that a frequent re-adjustment of the adjusting positions given by the characteristic diagram of engine timing is required and/or higher oil flow rates have to be provided for.
From another actuating device for a camshaft disclosed in DE-OS 39 22 962, it is further known to make axial and radial grooves in the wings of the winged wheel and arrange spring-mounted seals in these grooves to sealingly cooperate with the circumferential wall and the side walls of the hollow space of the drive pinion.
The manufacturing of vane-type adjusting devices with such sealing measures has proved to be very complicated and expensive, and, due to the transition junctions between the individual axial and radial seals, these sealing measures cannot assure a satisfactory reduction of leakage values.